Semiconductor device with a contact plug adjacent a gate structure

Abstract

A semiconductor device includes a substrate, a gate structure on the substrate, a first etch stop layer, a second etch stop layer, and an interlayer insulation layer that are stacked on the gate structure, and a contact plug penetrating the interlayer insulation layer, the second etch stop layer, and the first etch stop layer and contacting a sidewall of the gate structure. The contact plug includes a lower portion having a first width and an upper portion having a second width. A lower surface of the contact plug has a stepped shape.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a gate structure on a substrate, the gate structure comprising:
 a gate electrode structure; 
 first and second gate spacers that are on opposite sidewalls of the gate electrode structure; and 
 a capping pattern on the gate electrode structure and the first and second gate spacers; 
 
 first and second source/drain layers on the substrate adjacent to the first and second gate spacers, respectively, of the gate structure; and 
 first and second contact plugs vertically overlapping the first and second source/drain layers, respectively, 
 wherein a lower surface of the capping pattern is curved, 
 wherein the first contact plug directly contacts the first gate spacer of the gate structure, and the second contact plug is spaced apart from the second gate spacer of the gate structure, and 
 wherein the first contact plug comprises a stepped-shape sidewall that does not overlap with and is not aligned with the stepped-shape sidewall of the first source/drain layer. 
 
     
     
       2. The device of  claim 1 , wherein a middle lower surface of the capping pattern is higher than an edge lower surface of the capping pattern. 
     
     
       3. The device of  claim 2 , wherein the edge lower surface of the capping pattern has a downward convex curved shape. 
     
     
       4. The device of  claim 1 , wherein the first contact plug includes a lower portion having a first width and an upper portion having a second width greater than the first width. 
     
     
       5. The device of  claim 4 ,
 wherein the lower portion of the first contact plug is positioned below a height level of an upper surface of the gate structure, 
 wherein the upper portion of the first contact plug is positioned equal to or above the height level of the upper surface of the gate structure, and 
 wherein a first sidewall of the first contact plug contacting the first gate spacer of the gate structure is bent at the height level of the upper surface of the gate structure. 
 
     
     
       6. The device of  claim 5 , wherein a second sidewall of the first contact plug has a constant slope with respect to an upper surface of the substrate. 
     
     
       7. The device of  claim 1 , further comprising:
 an insulating interlayer between the second gate spacer of the gate structure and the second contact plug. 
 
     
     
       8. The device of  claim 1 , wherein the gate electrode structure comprises:
 a gate electrode; and 
 a gate insulation pattern on a sidewall of the gate electrode and a lower surface of the gate electrode. 
 
     
     
       9. The device of  claim 1 , further comprising:
 a first metal silicide pattern between the first source/drain layer and the first contact plug; and 
 a second metal silicide pattern between the second source/drain layer and the second contact plug. 
 
     
     
       10. The device of  claim 1 , wherein the lower surface of the capping pattern is curved with a rounded convex shape towards the substrate that contacts the gate electrode structure and has curved portions in contact with the first and second gate spacers. 
     
     
       11. A semiconductor device comprising:
 a first gate structure on a substrate; 
 a second gate structure on the substrate, the second gate structure being spaced apart from the first gate structure; 
 a first source/drain layer on the substrate between the first and second gate structures; 
 a second source/drain layer on the substrate adjacent to the second gate structure; 
 a first contact plug vertically overlapping the first source/drain layer; and 
 a second contact plug vertically overlapping the second source/drain layer, 
 wherein an edge upper surface of the first source/drain layer is higher than a central upper surface of the first source/drain layer, 
 wherein a central lower surface of the first contact plug is lower than an edge lower surface of the first contact plug, and 
 wherein a lower surface of the second contact plug extends beyond an upper surface of the second source/drain layer in a cross-sectional view. 
 
     
     
       12. The device of  claim 11 , further comprising:
 a metal silicide pattern between the first source/drain layer and the first contact plug. 
 
     
     
       13. The device of  claim 11 , further comprising:
 an insulating interlayer between the first contact plug and a first sidewall of the first gate structure. 
 
     
     
       14. The device of  claim 13 , further comprising:
 a second contact plug contacting a second sidewall of the first gate structure. 
 
     
     
       15. The device of  claim 14 , wherein the second contact plug includes a lower portion having a first width and an upper portion having a second width greater than the first width. 
     
     
       16. The device of  claim 15 ,
 wherein the lower portion of the second contact plug is positioned below a height level of an upper surface of the first gate structure, 
 wherein the upper portion of the second contact plug is positioned equal to or above the height level of the upper surface of the first gate structure, and 
 wherein a sidewall of the second contact plug contacting the second sidewall of the first gate structure is bent at the height level of the upper surface of the first gate structure. 
 
     
     
       17. The device of  claim 11 ,
 wherein a first sidewall of the first source/drain layer is vertically aligned with a substantially flat first sidewall of the first contact plug, and the first contact plug extends beyond a second sidewall of the first source/drain layer in a cross sectional view, and 
 wherein the first contact plug comprises a stepped-shape second sidewall that does not overlap with and is not aligned with the second sidewall of the first source/drain layer.